94 lines
2.8 KiB
Go
94 lines
2.8 KiB
Go
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// Copyright 2019 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package connectivity implements client connectivity operations.
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package connectivity
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import (
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"sync"
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"go.uber.org/zap"
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"google.golang.org/grpc/connectivity"
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)
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// Recorder records gRPC connectivity.
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type Recorder interface {
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GetCurrentState() connectivity.State
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RecordTransition(oldState, newState connectivity.State)
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}
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// New returns a new Recorder.
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func New(lg *zap.Logger) Recorder {
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return &recorder{lg: lg}
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}
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// recorder takes the connectivity states of multiple SubConns
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// and returns one aggregated connectivity state.
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// ref. https://github.com/grpc/grpc-go/blob/master/balancer/balancer.go
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type recorder struct {
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lg *zap.Logger
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mu sync.RWMutex
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cur connectivity.State
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numReady uint64 // Number of addrConns in ready state.
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numConnecting uint64 // Number of addrConns in connecting state.
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numTransientFailure uint64 // Number of addrConns in transientFailure.
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}
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func (rc *recorder) GetCurrentState() (state connectivity.State) {
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rc.mu.RLock()
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defer rc.mu.RUnlock()
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return rc.cur
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}
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// RecordTransition records state change happening in subConn and based on that
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// it evaluates what aggregated state should be.
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//
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// - If at least one SubConn in Ready, the aggregated state is Ready;
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// - Else if at least one SubConn in Connecting, the aggregated state is Connecting;
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// - Else the aggregated state is TransientFailure.
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//
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// Idle and Shutdown are not considered.
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//
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// ref. https://github.com/grpc/grpc-go/blob/master/balancer/balancer.go
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func (rc *recorder) RecordTransition(oldState, newState connectivity.State) {
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rc.mu.Lock()
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defer rc.mu.Unlock()
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for idx, state := range []connectivity.State{oldState, newState} {
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updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new.
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switch state {
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case connectivity.Ready:
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rc.numReady += updateVal
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case connectivity.Connecting:
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rc.numConnecting += updateVal
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case connectivity.TransientFailure:
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rc.numTransientFailure += updateVal
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default:
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rc.lg.Warn("connectivity recorder received unknown state", zap.String("connectivity-state", state.String()))
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}
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}
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switch { // must be exclusive, no overlap
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case rc.numReady > 0:
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rc.cur = connectivity.Ready
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case rc.numConnecting > 0:
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rc.cur = connectivity.Connecting
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default:
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rc.cur = connectivity.TransientFailure
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}
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}
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